Tech Note 13.1 – Stainless for Street Furniture

At Draffin, in over 60 years of operation we have acquired a huge amount of experience with street furniture. We would like to share our experience with you. The below tech note is some basics on stainless steel, but if you are interested and would like any more information or advice, or we can help in any other way, please call one of our friendly staff today.

Tech Note 13.1 Stainless Steel for Street Furniture

Everyday we use stainless steel, from the spoon we eat our Weeties with to the steel ruler on our desk. Stainless steel is also playing a major part in urban furniture. Generally specified for its extreme durability or its attractive finish, stainless steel can also be a cost effective option when a full life cycle is taken into account. Other commonly used materials such as powder-coated steel, galvanised steel, aluminium, recycled plastic and timber can last for long periods of time under certain circumstances, but are prone to corrosion, fading, cracking, graffiti damage and a myriad of other threats that will reduce the visual appeal of the furniture prematurely and eventually fail structurally

Some of the advantages of Stainless Steel

Sleek modern aesthetics

Very high resistance to corrosion

Easy to clean and sanitise

Easy to remove graffiti

Long life cycle, 20 years plus

Highly recyclable

Little to no ongoing maintenance

A Financially Sensible Decision

Although material costs are generally higher than coated mild steel items, stainless steel can actually be a sound economic decision. Typically capital investment will be 30-40% more than coated mild steel, but can have up to double the expected life cycle.

Environmental Impact

Stainless Steel is 100% recyclable, and given the long life cycle and low maintenance inputs, it can be a more environmentally friendly option than alternative materials, such as aluminium with extremely high energy inputs.

The Basics of Stainless

Stainless Steel is not a complicated material to work with, but it is important to have an understanding of the basics when specifying.

Grades of Stainless Steel

304

Is 18% chromium and 8% nickel (18/8) – A highly durable material suitable for indoor and some outdoor applications. It is the most commonly used stainless steel. 304 is not suitable for coastal or other aggressive environments. Although it will retain its structural integrity, it may show signs of unsightly surface corrosion known as tea staining.

316

Is 18% chromium and 10% nickel (18/10) – Commonly known as marine grade stainless, the extra nickel content adds some extra resistance to corrosion. Suitable for marine and other aggressive environments 316 is a safe choice for urban furniture, but is more expensive than 304.

Welding

Two types of welding are typically employed when fabricating stainless steel.

MIG Welding

MIG welding, or Metal Inert Gas, is a fast and easy method of welding. Rollers feed a continuous filler wire through a contact tip shrouded by an Inert Gas. When the filler wire meets the work piece the circut is completed there is an arc which melts the filler wire and parent metal together. Stainless MIG welding is suitable for hidden areas on heavier metals as it is a more economical option, but is prone to issues such as contaminated welds, spatter (weld over spray), and cannot create as controlled and neat weld as TIG.

TIG Welding

TIG welding, or Tungsten Inert Gas, is employed where a more controlled, stronger weld is required. Using an electric flame torch shrouded in inert gas, TIG operators can precisely control heating of parent metals and manually feed filler wire as required. Tig welding produces a deeper penetration, smaller welds and a visually appealing look.

Surface Finishes

Surface finishing is the last process in stainless fabrication. Good surface finishing is what seperates a good job from a great job. The smoother the surface finish the greater the corrosion resistance, as contaminants will not be caught in the grooves of the surface, promoting tea staining. Below are the most common finishes used on urban furniture.

Mill Finish (2B)

Finish is as the material comes off the production line. Best used for applications where the finish is not a factor, such as a hidden framing.

Brush (No4, No6)

Achieved by mechanical abrasion, brush finishing brings the material to a shiny finish, but also imbeds a directional grain into the surface.The smoother the brush finish the better the corrosion resistance.

Mirror (No8)

Achieved by buffing the surface to reflective finish. Mirror finishes are used for aesthetic reasons, but can also provide the functional advantage of being easy to clean and more resistant to tea staining.

Pickle and Passivation

Using chemicals pickling removes all surface contaminants post fabrication, and passivating accelerates the production of the passive layer which increases corrosion resistance.

Electro polish

Electro polishing is regarded as the highest form of corrosion resistance and is an anodic process that selectively removes surface flaws and imbedded impurities, as well as high points in the surface layer.

Draffin Street Furniture and Stainless

Draffin have a long history of using stainless steel for urban furniture, and love to use our experience and expertise to create exceptional solutions. Below are some of the examples where we have used stainless steel in our products. If you wish to discuss how you could use stainless steel please call one of our friendly designers.